Fickle like the wind, it burns like the sun. The Dark Side of Renewable Energy

Renewable energy sources are not only dreams, hopes and optimistic forecasts. The truth is also that renewables are causing a lot of confusion in the energy world and causing problems that traditional grids and systems can't always handle. Their development brings many unpleasant surprises and questions that we cannot answer yet.

Energy produced in renewable energy sources - wind farms and photovoltaic installations - is a real challenge for national energy systems.

The power consumption of the network is not constant. It is subject to daily fluctuations in a fairly large range of values. Its regulation by the power system remains difficult, since it is associated with the need to ensure the appropriate parameters of the mains current (voltage, frequency). In the case of conventional power plants, such as a steam turbine, power reduction is possible by reducing the steam pressure or the speed of rotation of the turbine. Such regulation is not possible in a wind turbine. Rapid changes in wind strength (such as storms) can admittedly generate significant power in a short time, but are difficult for the power grid to absorb. Power surges in the network or its temporary absence, in turn, pose a threat to end users, machines, computers, etc. smart grids, so-called equipped with appropriate tools, including energy storage systems, efficient and comprehensive distribution systems. However, there are still few such systems in the world.

Australian Greens artwork celebrating zero greenhouse gas emissions

Exceptions and unused powers

The blackouts that hit South Australia last September were caused by problems at nine of the thirteen wind farms that supply electricity to the region. As a result, 445 megawatts of electricity was lost from the grid. Although the wind farm operators assured that the breaks were not caused by fluctuations typical for wind power - that is, an increase or decrease in wind power - but by software problems, the impression of a not entirely reliable renewable energy was difficult to destroy.

Dr. Alan Finkel, who later researched the energy market on behalf of the Australian authorities, came to the conclusion that the development of renewable energy sources discriminates against the poorer sections of society. In his opinion, as the industry invests heavily in renewable energy, energy prices should rise, hitting the lowest income hardest.. This is true for Australia, which is shutting down its cheap coal power plants and trying to replace them with renewables.

Fortunately, the last coal-fired power plant in the aforementioned blackout-hit South Australia closed just before the problems described, in May 2016. Supply volatility is a well-known but still not very familiar problem with renewable energy. We also know him from Poland. If you combine the 4,9 GW of wind turbine capacity achieved on December 26, 2016, when Hurricane Barbara hit, with the generation of domestic turbines a week earlier, it turns out that it was then seventy times lower!

Germany and China have already realized that it is not enough to build windmills and solar panels to make the new energy work efficiently. The German government was recently forced to pay the owners of wind turbines that grow mushrooms to cut power because the transmission grids couldn't handle the load being delivered. There are problems in China too. There, coal-fired power plants, which cannot be switched on and off quickly, cause wind turbines to stand idle 15% of the time, since the grid cannot receive energy from power plants and turbines. That's not all. Solar power plants are being built there at such a pace that the transmission network cannot receive even 50% of the energy they generate.

Wind turbines are losing power

Last year, researchers at the German Max Planck Institute in Jena published a paper in the prestigious scientific journal Proceedings of the National Academy of Sciences (PNAS) showing that the efficiency of large wind farms is much lower than what could be simply the result of their scale. Why does the amount of energy received not depend linearly on the size of the plant? Scientists suggest that it is the windmills themselves that slow down the wind using its energy, which means that if there is a lot of it installed in a given area, then some of them will not receive it in sufficient quantities to work with maximum efficiency.

The researchers used data from a number of large wind farms and compared them with data from individual wind turbines to create a model based on already known models of wind mechanics. This made it possible to observe the climate in the region of windmills. As noted by Dr. Lee Miller, one of the authors of the publication, the estimated energy efficiency of insulated wind turbines is significantly higher than observed for their entire installations.

The scientists determined that, in the extreme case, a wind turbine located in an area of ​​high density of such installations could produce only 20% of the potentially available electricity if it were located alone.

The scientists used the developed impact model of wind turbines to estimate their global impact. This made it possible to calculate how much energy

Electricity can be generated on a global scale using wind turbines. It turns out that only about 4% of the earth's surface can potentially generate more than 1 W/m.²and on average about 0,5 W / m² – These values ​​are similar to previous estimates based on advanced climate models, but about ten times lower than estimates based solely on local mean wind speeds. This means that while maintaining the optimal distribution of wind turbines, the planet will be able to receive no more than about 75 TW of wind energy. However, this is still much more than the currently installed electrical capacity in the world (about 20 TW), so there is no reason to worry, given that there are only about 450 MW of wind power operating on Earth today.

Massacre of flying creatures

In recent years, there have been reports and information about the killing of birds and bats by wind turbines. There are known fears that machines, rotating in pastures, frighten cows, besides, they should produce harmful infrasound, etc. There are no convincing scientific studies on this subject, although reports of hecatombs of flying creatures are relatively reliable data.

Image from a thermal camera showing a bat flying near a wind turbine at night.

Every year, hundreds of thousands of bats attack wind farms. Treetop nesting mammals confuse air currents around windmills with currents around their homes, the site reported in 2014. Power plants should also remind bats of tall trees, in the crowns of which they expect clouds of insects or their own nest. This seems to be supported by thermal camera footage, which shows that bats behave in the same way with wind farms as they do with trees. Scientists claim that hundreds of thousands of bats could survive if the design of the rotor blades were changed. The solution is also to increase the threshold at which it starts spinning. Researchers are also thinking about equipping turbines with ultrasonic alarms to warn bats.

A register of collisions of these animals with wind turbines, for example for Germany, conducted by the Brandenburg State Environmental Protection Agency, confirms the massive nature of the deaths. The Americans also investigated this phenomenon, confirming the high mortality among bats, and it was noted that the frequency of collisions was highly dependent on weather conditions. At high wind speeds, the impact ratio was lower, and at lower wind speeds, the number of impact victims increased. The limiting wind speed at which the collision rate was significantly reduced was determined to be 6 m/s.

A bird burnt over the Ivanpa complex

As it turned out, unfortunately, the great American solar power plant Ivanpah also kills. Shortly after its launch, The Wall Street Journal announced that the Californian project could be the last of its kind in the US, precisely because of the avian hecatombs.

The complex occupies 1300 hectares in one of the Californian deserts, southwest of Las Vegas. It has three towers with a height of 40 floors and 350 thousand mirrors. Mirrors reflect sunlight towards the boiler rooms located on the tops of the towers. Steam is produced, which drives generators to produce electricity. Enough for 140 thousand. Houses. However the mirror system heats the air around the towers up to 540°C and the birds flying nearby simply burn alive. According to a Harvey & Associates report, more than 3,5 people died at the plant during the year.

Too much media hype

Finally, it is worth mentioning one more unfavorable phenomenon. The image of renewable energy often suffers from exaggeration and excessive media hype, which can mislead people about the real state of development of this technology.

For example, the headlines once announced that the city of Las Vegas was going completely renewable. It sounded sensational. Only after reading more carefully and deeper into the information provided, we found out that yes - in Las Vegas they are switching to 100% renewable energy, but only ... municipal buildings, which make up a fraction of a percent of buildings in this agglomeration.

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